1. Field of the Invention
The present invention relates to a method of assembling a carriage assembly for use in a magnetic disk apparatus, and in more detail to a method of assembling a carriage assembly assembled by crimping together carriage arms and suspensions.
2. Related Art
FIG. 8 schematically shows the overall construction of a carriage assembly used in a magnetic disk apparatus. The carriage assembly is formed by attaching suspensions 12 to the front ends of carriage arms 10, a plurality of which are disposed in parallel in accordance with the intervals at which magnetic media are disposed. A slider 14 equipped with a magnetic head used to record and reproduce information is mounted on the front end of each suspension 12. A flexible circuit board 16 is attached to side surfaces of the carriage arms 10, and the magnetic heads formed on the sliders 14 and a control unit 18 are electrically connected via the flexible circuit board 16.
FIGS. 9A and 9B show a conventional method of fixing (attaching) the suspensions 12 to the carriage arms 10. After the suspensions 12 have been set on the carriage arms 10 by aligning crimping portions 12a formed at base portions of the suspensions 12 with attachment holes 10a formed in the front ends of the carriage arms 10, a ball 20 made of metal and formed with a slightly larger diameter than an inner diameter of crimping holes 12b provided in the crimping portions 12a is pressed into the crimping holes 12b and is passed through the crimping holes 12b to fix the suspensions 12 to the carriage arms 10. Since the pressure/heat applying head 20 is formed with a slightly larger diameter than the crimping holes 12b, when the metal ball 20 passes through the crimping holes 12b, the crimping portions 12a are pressed open to fix the suspensions 12 to the carriage arms 10 by crimping.
Since deformation occurs due to the crimping when the ball 20 is pressed into the crimping holes 12b, ultrasonic vibration is conventionally applied to the crimping tool 22 to reduce the stress when the ball 20 is pressed into the crimping holes 12b, thereby reducing deformation of the suspensions 12 and the like.
It is believed that deformation of the suspensions 12 and the like can be reduced by applying ultrasonic vibration to the crimping tool when crimping the suspensions 12 to the carriage arms 10 using the ball 20 since the ultrasonic vibration causes the ball 20 to rotate when the ball passes through the crimping holes 12b, thereby reducing the load on the ball 20. Accordingly, when the ball 20 is pressed into the crimping holes while applying ultrasonic vibration to the crimping tool 22, it is possible to suppress the deformation caused by the crimping by preventing the rotation of the ball 20 from being obstructed.
Patent Document 1
Japanese Laid-Open Patent Publication No. 2004-127491
As magnetic disk apparatuses have become smaller, the carriage assemblies provided in magnetic disk apparatuses have been miniaturized, the suspensions mounted on the carriage assemblies have been miniaturized, and the thicknesses of the members have been reduced. Accordingly, when the suspensions are crimped onto the carriage arms, the suspensions 12 are susceptible to deforming when the crimping force becomes only slightly uneven.